FR2779001A1 - Experimental teaching apparatus for simulating effects of flowing water - Google Patents

Abstract

The apparatus comprises an elongated tank (11), made from molded plastic and shaped with a central lengthwise channel (12) representing a valley with various projections in its base (13) formed by islets (16) and raised banks (17). A feed system (30) with a pipe (31) and tap (32) delivers liquid into the upper end of the valley, and a secondary valley (18) in one side of the first can also be fed with liquid. At the lower end a vertical partition (21) represents a barrage, with a channel (22) downstream of it.

Description

The present invention relates to an experimental device with character

  educational aiming at simulating and quantifying the phenomena of erosion, transport and

sedimentation in a stream.

  As part of the study of natural sciences in schools, it is often interesting for both students and teachers to carry out practical work to visualize and concretely quantify the natural phenomena studied in the theoretical course. In the particular case of the practical study of the phenomena of erosion, transport and sedimentation in

  a watercourse, so far we have only used

  extremely summary tifs, generally consisting of a

  simple bin filled with sand. A recess symbolizing the bed of a watercourse is then hollowed out on the upper surface of the sand, and a flow of water is organized at one end of this recess which follows the bottom of said recess, in the manner of a stream. Such a device is of course too rudimentary to allow a

  quantifiable and varied appreciation of the different phenomena

  that can be encountered, associated with the flow of a

stream.

  There is therefore a need for a more

  developed to simulate qualitatively and quanitita-

  erosion, transport and sedimentation phenomena, and in particular making it possible to verify the so-called Hjulstrom physical law, an empirical law according to which a grain of given size is uprooted, transported or deposited at a given point in the watercourse , according to the

  water flow or the slope of the watercourse.

  The object of the invention is therefore to provide an experimentation device which is simple and easy to handle, and which thus allows a simulation and a quantification of the phenomena of erosion, transport and sedimentation in a watercourse, with in addition the possibility of easily varying the conditions of

liquid flow.

  This problem is solved in accordance with the invention by means of an educational experimentation device aimed at simulating and quantifying the phenomena of erosion, transport and sedimentation in a watercourse, comprising an elongated tank, the central part of which is hollowed out to form a valley ending in an uneven bottom, and a liquid supply means arranged at one end of the tank corresponding to the upstream of the symbolized stream. Thus, it suffices to deposit a certain amount of a granular material, for example sand, at the end of the tank corresponding to the upstream of the symbolized stream, then to organize the supply of the liquid arranged at

  level of this end, to recreate experimentally-

  tale and see evolving live many alluvial figures such that we can meet them in real life

  greatness with the bed of a river.

  Preferably, the uneven bottom presents at the

  minus a raised island and / or raised banks.

  We can also provide that the recess in the central part also forms a secondary valley opening into the aforementioned valley, so as to simulate a

tributary of the watercourse.

  It is also interesting to provide that the recess in the central part forms, on one side. from the valley, a valley advancing towards the center of the symbolized stream.

  0 In accordance with a particular mode of execution-

  ment simple, we can provide that the liquid supply means comprises a pipe fixed by an associated tab on a vertical end wall of the elongated tank, said pipe being connected to a source of liquid by an operating valve. Optionally, the device may include at least one additional means of supplying liquid, under

  form of another pipe, the end of which can be moved.

  Preferably, the other end of the elongated tank, corresponding to the downstream of the symbolized stream, will have a central vertical wall forming a dam. In particular, the elongated container may have, on the other side of

  the vertical wall forming a dam, a channeling space

  tion and / or receiving liquid.

  Advantageously also, the elongated container may have a gunwale with a sinuous central cut forming

the upper edge of the valley.

  Preferably, finally, the elongated tank is constituted by a light, one-piece hollow plastic body, produced by molding, and having a substantially constant low thickness. There is then an easy-to-handle monobloc assembly which can be inclined longitudinally and / or transversely by using

adequate shims.

  Other features and advantages of the

  vention will appear more clearly in light of the

  description which follows, concerning a mode of exe (ution

  particular, with reference to Figures o:

  - Figure 1 illustrates in perspective a device

  tif of educational experimentation in accordance with the invention, as it appears before its practical use; - Figure 2 illustrates the same device in use, after displacement of a certain amount of grains of sand from an initial deposit made upstream, with in addition a supply of liquid

  additional at the level of a secondary valley.

  FIG. 1 makes it possible to distinguish an experimentation device of an educational nature denoted 10, essen-

  tially constituted by an elongated tank 11, the central part of which is hollowed out to form a valley 12 ending in an uneven bottom 13, a means 30 for supplying liquid being arranged at one end 15 of the tank 11 corresponding to

upstream of the symbolized river.

  In this case, an elaborate construction of the central valley 12 and of the uneven bottom 13 has been planned, so as to

  to reproduce different relief sites allowing

  kill several types of experiments with flows of

  liquid and alluvial movements.

  Thus, the uneven bottom 13 has at least one raised island 16 (four are distinguished here), and

  raised banks denoted 17, here three in number.

  The raised islands 16 and the raised banks 17 thus detach from the rest of the uneven bottom 13 which is

essentially flat.

  The elongated tank 11 is here of generally parallelepipedal shape, and has a gunwale 14 with a sinuous central cut 25 forming the upper edge of the valley 12. One end 15 of the elongated block 11 constitutes the upstream end of the device (here the right end in the figure). This end 15 of the tank 11, which corresponds to the upstream of the symbolized stream, is equipped with the means 30 for supplying the liquid, which here consists of a flexible pipe 31 fixed by an associated tab 34 on the vertical wall from end 15, said pipe being connected to a

  source of liquid arriving via a pipe 33 via

  diary of a maneuvering tap 32. By opening the maneuvering tap 32, we thus realize a water supply, read at the level of the upstream of the symbolized stream, and the ecu then flows by following the profile drawn by bathing the uneven bottom 13, as well as the contours of the two banks,

  the raised islands 16, and the raised banks 17.

  In order to be able to vary the experiences even further, it has been planned that the recess in the central part also forms a secondary valley denoted 18, opening into the aforementioned main valley 12, so as to simulate a tributary of the watercourse. As illustrated in FIG. 2, it then suffices to provide an additional means for supplying liquid, for example in the form of another pipe 35 the end of which can be moved, to organize an additional supply of liquid in a lateral way, like a tributary of a river. It has also been provided here that the recess in the central part forms, on one side of the valley 12, a valley denoted 19 advancing towards the center of the symbolized stream. With the aforementioned pipe 35, it is then easy to organize a secondary flow of

  liquid on either side of the valley 19.

  The other end of the elongated tank 11, denoted 20, corresponds to the downstream of the watercourse symbolizes. This end 20 here has a central vertical wall 21 forming a barrier. Downstream of this vertical wall 21, there is, between two portions of gunwale 14, a space denoted 22 for channeling and / or receiving liquid, delimited by two vertical walls, 23, here forming a constriction

from upstream to downstream.

  The elongated container 11 will preferably be constituted by a light, one-piece hollow plastic body, produced by molding, and having a substantially constant thickness. In this case, this block thus has the form of a flat parallelepiped of around 5 cm in height, the side walls of which are noted 26. This parallelepipedal block is hollow below, so that it

  constitutes a kind of elongated plate light to handle.

  It therefore becomes extremely easy to modify the longitudinal and / or transverse inclination of the elongated container 11l

  by inserting suitable shims (not shown here).

  This then makes it possible to vary the flow conditions very easily, and thus opens the door to

  very varied practical experiences.

  During practical work, a certain amount of sand is deposited at the level of the amonL end, then the supply of liquid is triggered by manipulating the valve 32. The water passing over the sand then implements erosion phenomena , transport and sedimentation, like the phenomena encountered in reality with a real river. We can then see many dB of alluvial figures evolving in dBrect, such as: - various processes and forms of erosion, with a sandy micro-cliff, or an asymmetry of concave, and / or convex banks, or the erosion of a bench, meander, etc ...; - an alluvial transport, by varying the transport speed as a result of a change in the flow rate of the liquid supplied: this is how we can corroborate by experience the theoretical diagram Hjulstrôm, according to which a grain of given size is torn off, or transported, or deposited at a given point in the watercourse, depending on the water flow and the slope of the watercourse; a materials depot, with the formation of benches

  sandy, dead arms, meanders, or with sedimenta-

  Lion in a lake or delta type body of water.

  The sedimentary processes and figures naturally evolve according to the variation of the parameters concerned. In order to vary the nature of the materials, we can use clay, diluted mud in water, topsoil, sand, sand, small gravel or gravels. it is also interesting to create a mixture of different materials, possibly with different colors to facilitate visual observation, in order to observe the difference in behavior of the materials. It is also possible to add small branches a few centimeters long so as to simulate the uprooting and the

  transport of tree trunks during a flood.

  We can also simulate the variations in the quantity of alluvium, by varying the quantity of material deposited upstream of the valley, as well as the frequency of

these deposits.

  In practice, it will be necessary to recharge regularly at the start of the experiment to create the

  first sedimentary areas and regularize the functioning

  is lying. In particular, we can simulate sediment overloads by varying the quantity of materials at the same time as the flow, like a flood or a landslide blocking the bed of a mountain river.

for example.

  We can of course observe the effects of the inclination of the bottom of the bed, by varying the slope of the elongated tank (in a longitudinal and / or transverse direction). It will then be easy to observe that with the same constant flow, the alluvial activity changes in

  function of the inclination. In addition, by rocking lightly-

  the elongated container on one side or the other, the arrangement

  tion of the bottom and the alluvial mode is modified accordingly.

  Finally, by playing on the liquid flow rate, it is possible to simulate floods and low flow rates.

  However, it is interesting to leave a regular flow25 for a long time, because this makes it possible to regularize the alluvial process, and to obtain areas of beaches and banks, and areas cleared by erosion, which correspond to a dynamic balance. At this time, the phenomena of erosion, transport and sedimentation cease, and a very characteristic alluvial "landscape" is obtained. Such a landscape is illustrated in FIG. 2, and it can be seen that sand 40 has spread over the uneven bottom 13 of the elongated tank 11 as a result of a main flow of liquid shown diagrammatically by the arrow 50, and possibly of a complementary flow through the secondary valley 18 shown diagrammatically by the arrow 51. The arrow 52 serves to diagram the flow of the liquid downstream of the wall forming a dam 21. The presence of the valley 19 also makes it possible to simulate disturbances brought about in the general course of the 'central flow. This small active valley corresponds, for example, to a very strong thunderstorm located over a basin, lateral slope to a larger river in the mountains for example. We can use the pipe 35 shown in Figure 2, or alternatively use a watering can with its apple to simulate rain, or without its apple to simulate a simple flow at the bottom

bed.

  Along the length of the uneven bottom, there are thus different zones of sand 40 corresponding to zones of sedimentation, and of erosion and of transport,

  according to the Hjulstrom diagram.

  We could thus observe the behavior of a grain of 1 mm in diameter: with a speed of one centimeter per second for the current, the grain settles or remains on the bottom, while with a speed of 10 centimeters per second, the grain is transported by the current but is not torn from the bottom; finally, if the speed of the current is 100 centimeters per second, the grain is then

  torn from the bottom and transported.

  Once the experiments are finished, it is easy to remove the sand which has been used, and to remove the sand which has served by a simple spray of water directed on the central valley 12 of the elongated tank 11, and to store the tank before

another later experience.

  We have thus succeeded in achieving an experimental device of educational nature which is

  simple structure, and allows multiple experienices used to simulate and quantify different phenomena of erosion, transport and sedimentation in a watercourse.

  The invention is not limited to the embodiment which has just been described, but on the contrary encompasses any variant using, with equivalent means, the

  essential characteristics stated above.

Claims (10)

RESELL I CATIONS   1. Experimental device for educational purposes aimed at simulating and quantifying the phenomena of erosion, transport and sedimentation in a watercourse, characterized in that it comprises an elongated tank (11), the central part of which is hollowed out to form a valley (12) ending in an uneven bottom (13), and a means (30) for supplying liquid arranged at one end (15) of the tank   (11) corresponding to the upstream of the symbolized watercourse.   2. Device according to claim 1, character-   laughed in that the uneven bottom (13) has at least one   raised island (16) and / or raised banks (17).   3. Device according to claim 1 or claim 2, characterized in that the recess in the central part also forms a secondary valley (18) opening into the aforementioned valley (12), so as to simulate   a tributary of the watercourse. 4. Device according to one of claims 1 a   3, characterized in that the recess in the central part   form, on one side of the valley (12), a valley (19) advancing towards the center of the symbolized stream.   5. Device according to one of claims 1 to   4, characterized in that the means (30) for supplying liquid comprises a pipe (31) fixed by an associated tab (34) on a vertical end wall (15) of the elongated tank (11), said pipe being connected to a source of liquid by a operating valve (32).   6. Device according to claim 5, character ized in that it comprises at least one additional means (35) for supplying liquid, in the form of another pipe,   the end can be moved.   7. Device according to one of claims 1 to   6, characterized in that the other end (20) of the elongated tank (11), corresponding to the downstream of the symbolized stream, has a central vertical wall (21) forming a dam.   8. Device according to claim 7, calracte-   laughed in that the elongated container (11) has, on the other side of the vertical wall (21) forming a barrier, a space (22) for channeling and / or receiving liquid.   9. Device according to one of claims 1 to   8, characterized in that the elongated container (11) is generally rectangular in shape, and has a gunwale (14) with a sinuous central cutout (25) forming the upper edge from the valley (12).   10. Device according to one of claims 1   9, characterized in that the elongated container (11) is made up of   killed by a light one-piece hollow plastic body, produced by molding, and having a small thickness substantially constant.